1. Field of the Invention
The present invention relates to a reflection mirror and optical equipment using the reflection mirror, which is stable, has satisfactory durability, and provides a high reflectance, for example, in a predetermined wavelength band in a visible range (wavelength: 400 to 700 nm), and is suitable when applied to an optical member used in an optical system such as a TV camera, a video camera, a digital camera, or the like.
2. Related Background Art
Conventionally, a number of exemplary reflection mirrors using an Al film are known. Recently, however a silver reflection mirror comes to be known, which is obtained by vapor-depositing a silver film having a high reflectance in a wavelength of a wide visible range on a resin substrate.
The silver film as the reflection film has a high reflectance. However, when exposed to the outside air, the silver film corrodes to decrease a reflectance. Thus, the silver film has weak resistance to the environment.
Because of the above, the reflection mirror using a silver film requires measures for providing a protective film for covering the silver film so as to enhance the durability with respect to the environment, for example.
Japanese Patent Application Laid-Open No. H5-127005 or Japanese Patent Application Laid-Open No. H6-313803 discloses a reflection mirror using a sulfide in an underlaying layer (a film provided between a substrate and a silver film) or a protective film for a silver film.
On the other hand, Japanese Patent Application Laid-Open No. H7-005309, Japanese Patent Application Laid-Open No. H8-327809, or Japanese Patent Application Laid-Open No. 2001-074922 discloses a reflection mirror using a gold layer film in an underlaying layer or a protective film for a silver film.
In addition, reflection mirrors composed of a silver film which another material (e.g., Pd, Al or Au) is added to are also known.
In the reflection mirrors proposed by the above-mentioned applications, a resin substrate is used in place of a glass substrate, and measures are adopted in order to prevent decreases in durability and reliability (film peeling, fogging, etc.) caused when using an Ag film in place of an Al film.
However, in the reflection mirrors proposed in the above-mentioned applications, although the enhancement of durability and reliability are recognized, there is a tendency that an initial reflectance after forming a film becomes unstable. Furthermore, as a result of a reliability test such as an adhesion test using a tape, a high-temperature test at 80° C. for 100 hours, and an environmental test at 60° C. and a humidity of 90% for 1,000 hours, film peeling, fogging, and the like occurred in some cases.